You removed double the intended amount when fine-tuning a tenon to fit a mortise, instead of half from each side. Solution: To avoid cutting too much off a tenon when making microadjustments, leave reminders where they will be seen. Write the word "half" on the tenon cheeks and also on a piece of tape near the fine adjustment knob of your tenoning jig, as shown. Then split the difference between both sides when you need to remove more. Similar errors can happen when machining half-laps, and the solution works the same.